The manufacture of composite webs that exhibit elasticity, i.e., the ability to at least partially recover their original shape after moderate elongation, may be desired for a number of reasons. For example, elasticity may be useful in connection with fastening systems for items such as garments (e.g., diapers, training pants, gowns, bedding, etc.). Elasticity in garments can provide what may be referred to as dynamic fit, i.e., the ability to stretch and recover in response to movement by the wearer.
Elasticity may also be useful in connection with other articles or devices. For example, some fasteners may provide more consistent attachment if the fastener is held in tension that can be supplied by stretching the fastener and relying on the recovery forces to provide the desired tension. In other instances, elasticity may allow for easy adjustment of the size or length of a fastener or other article.
Although elasticity may be beneficial in a variety of different applications, it may raise issues in manufacturing. Many attempts to provide elasticity to, e.g., composite webs and other articles, rely on separate elastic components that are, e.g., glued or sewn to a substrate or other nonelastic member to provide the desired elasticity. The manufacture of such composite articles may be problematic in that secure attachment of the elastic components may be difficult to achieve and/or maintain. When attaching elastic components using adhesive (e.g., pressure sensitive adhesive), a common problem is adhesive creep, i.e., the tendency of the elastic component to move across the surface of the web or other article in response to shear forces.
Further, the cost and difficulty of providing and attaching separate elastic components may be relatively high. The handling and attachment of separate elastic components can reduce throughput, cause additional waste (where the separate components are not securely attached), etc.
In other instances, an entire composite web or substrate may exhibit elasticity. For example, many elastic fastening systems rely on the use of elastic laminate backings in which the elastic materials are provided in the form of a film that is coextensive with a substrate. Such an approach may add costs associated with providing a coextensive elastic layer or layers. Further, many elastic materials are not breathable. If the elastic laminate backings are to be used in garments, it may be desirable to perforate the backing to improve its breathability. Such additional processing does, however, add to the cost of producing the elastic laminate backing. Another potential disadvantage of elastic laminate backings is that it may be difficult to provide any adjustment of the elastic recovery forces generated in different portions of the backing.
While a variety of approaches to providing discrete polymeric structures on substrates are disclosed in, e.g., U.S. Patent Application Publication No. U.S. 2003/0087059 A1, filed 5 Nov. 2001 and titled COMPOSITE WEBS WITH DISCRETE ELASTIC POLYMERIC REGIONS, now abandoned, and U.S. Pat. Nos. 7,037,457 (Seidel et al.), 6,875,710 (Eaton et al.), 6,942,894 (Alberg et al.), 7,238,314 (Jackson et al.), and 7,195,729 (Jackson et al.), these approaches may be limited in certain aspects, such as in roll temperatures, the composition of substrates, etc. and those limitations may or may not apply in connection with the present invention.